Rear bumper for an automobile



FIG. 1 is a perspective view of a rear bumper for an automobile, showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a top plan view thereof:

FIG. 4 is a right side elevation view thereof; and,

FIG. 5 is a left side elevation view thereof.

The broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for, a rear bumper for an automobile, as shown and described. 